This invention relates to a method and apparatus for applying a coating of molten metal, and more particularly it relates to a method and apparatus for providing a metallic coating on the surface of a steel strip with coating rolls.
A widely known strip plating method comprises continuously supplying a molten coating metal so that a uniform film of the metal is formed on the peripheral surface of a coating roll and bringing a steel strip, continuously traveling in its longitudinal direction in contact with the coating roll.
Steel strips with such metallic coatings as zinc and tin are used for various applications. Some uses call for plating on one side only, and others demand plating of different metals on both sides. Some orders specify that neither side be plated.
None of the conventional metallic coating apparatus has permitted a choice from among such one-side, two-side and no-plating operations on a single unit. For example, U.S. Pat. No. 2,937,108 discloses a method of plating both sides of a strip, and U.S. Pat. No. 3,228,788 discloses a one-side strip plating method. Neither of them permits switching from one-side plating to two-side plating or vice versa, or plating different metals on opposite sides. Provision of separate units for one-side and two-side plating is uneconomical in terms of both capital investment and running cost.